Use of crosslinked polymers for lowering the cold filter plugging point of fuels

ABSTRACT

The present invention concerns the use, for lowering the cold filter plugging point of a fuel composition, of one or more crosslinked polymers comprising at least one unit of the following formula (I): in which R 1  represents a hydrogen atom or a methyl group; E represents —O—CO—, or —CO—O— or —NH—CO— or —CO—NH—; and G represents a C 1  to C 34  alkyl group; said copolymer having a crosslinking rate of between 0.5 mol % and 30 mol %. The invention also concerns additive compositions containing such a polymer, and fuel compositions with such polymers as additives, in combination with a cold flow improver (CFI) chosen from the copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s).

The present invention relates to the use of particular crosslinked polymers for lowering the cold filter plugging point of fuels during their storage and/or use at low temperatures.

The present invention also relates to additive compositions (or “additive packages”) containing such polymers, as well as fuel and fuel compositions additized with such polymers in combination with a cold flow improver (CFI).

PRIOR ART

Fuels containing paraffinic compounds, in particular compounds containing n-alkyl, iso-alkyl or n-alkenyl groups such as paraffinic waxes, are known to exhibit deteriorated flow properties at low temperatures, typically below 0° C. In particular, middle distillates obtained by distillation from crude oils of petroleum origin such as diesel or domestic heating fuels are known to contain different amounts of n-alkanes or n-paraffins depending on their origin. These compounds tend to crystallize at low temperatures, clogging pipes, ducts, pumps and filters, for example in the fuel systems of motor vehicles. In winter or under conditions of use of fuels at temperatures below 0° C., the crystallization of these compounds can lead to a reduction in the flow properties of fuels and, consequently, to difficulties in their transport, storage and/or use. The cold operability of fuels is a very important property, particularly for ensuring cold engine starting. If paraffins are crystallized at the bottom of the tank, they can be carried along in the fuel system when starting and clog, in particular, the filters and prefilters upstream of the injection systems (pump and injectors). In the same way, for the storage of domestic heating fuels, if paraffins precipitate at the bottom of the tank, they can be entrained and clog the pipes upstream of the pump and the boiler feed system (nozzle and filter).

These problems are well known in the field of fuels, and many additives or additive mixtures have been proposed and marketed to reduce the size of paraffin crystals and/or change their shape and/or prevent them from forming. The smallest possible crystal size is preferred as it minimizes the risk of filter plugging or clogging.

The usual flow improvers known as cold flow improvers (CFI) are generally copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s), used alone or in mixtures. These cold flow improvers (CFI), for lowering the cold filter plugging point (CFPP), inhibit crystal growth at low temperature by promoting the dispersion of paraffin crystals; they are, for example, ethylene/vinyl acetate (EVA) and/or ethylene/vinyl propionate (EVP) polymers, also commonly known as CFPP additives. This type of additive, which is widely known to the industry, is systematically added to conventional middle distillates at the refinery outlet. These additized distillates are used as fuel for diesel engines or as heating fuel. Additional quantities of these additives may be added to fuels sold at service stations, in particular to meet so-called “extreme cold” specifications.

To improve the CFPP of distillates, it is known to add to these CFI additives additional additives or “boosters” that act in combination with the CFI additives to increase their efficiency. Such additive combinations are extensively described in the prior art.

By way of example, mention may be made of the U.S. Pat. No. 3,275,427 describing a middle distillate of distillation cut between 177 and 400° C. containing an additive consisting of 90 to 10% by mass of an ethylene copolymer comprising 10 to 30% vinyl acetate units with a molar mass between 1000 and 3000 g/mol and 10 to 90% by mass of a poly(lauryl acrylate) and/or a poly(lauryl methacrylate) with a molar mass varying from 760 to 100 000 g/mol.

The document EP0857776 proposes the use of alkylphenol-aldehyde resins derived from the condensation of alkylphenol and aldehyde in combination with ethylene/vinyl ester copolymers or terpolymers to improve the fluidity of mineral oils.

The patent application WO 2008/006965 describes the use of a combination of a homopolymer obtained from an olefinic ester of a carboxylic acid of 3 to 12 carbon atoms and a fatty alcohol comprising a chain of more than 16 carbon atoms and optionally an olefinic double bond and an EVA or EVP type cold flow improver (CFI), to increase the effectiveness of CFI additives by amplifying their effect on the CFPP.

The patent application WO 2016/128379 describes the use, as a fuel cold flow improver, of a block copolymer comprising:

(i) a block A consisting of a chain of structural units derived from one or more α,β-unsaturated alkyl acrylate or methacrylate monomers,

(ii) a block B consisting of a chain of structural units derived from one or more α,β-unsaturated monomers containing at least one aromatic core.

This additive is particularly useful as a CFPP booster in combination with a cold flow improver (CFI).

Due to the diversification of fuel sources, there remains a need to find novel additives for lowering the cold filter plugging point of fuels.

This need is particularly great for fuels containing one or more paraffinic compounds, for example compounds containing n-alkyl, iso-alkyl or n-alkenyl groups with a tendency to crystallize at low temperatures.

In particular, the distillates used in fuels are increasingly derived from refining operations that are more complex than those derived from straight petroleum distillation, and may come from cracking, hydrocracking, catalytic cracking and visbreaking processes, among others. With the growing demand for diesel fuels, refiners tend to introduce more difficult cuts into these fuels, such as the heavier cuts from cracking and visbreaking processes that are rich in long-chain paraffins.

In addition, synthetic distillates from gas processing such as those from the Fischer-Tropsch process, as well as distillates resulting from the processing of plant or animal biomass, such as NExBTL and distillates comprising esters of vegetable or animal oils have appeared on the market, and constitute a new range of products that can be used as a basis for formulating diesel and/or domestic heating fuels. These products also include long-chain paraffinic hydrocarbons.

In addition, new crude oils have come onto the market, oils which are much richer in paraffins than those commonly refined and whose plugging point of the distillates from direct distillation was difficult to improve by conventional filterability additives in the same way as those mentioned above.

It was found that the low-temperature performance of distillates obtained by combining old bases and these new sources were difficult to improve by adding conventional filterability additives, among other things because of the high presence of long-chain paraffins and the complex distribution of paraffins in their composition. These new combinations of distillates were indeed noted to contain discontinuous distributions of paraffins, in the presence of which the known filterability additives are not always sufficiently effective.

There is therefore a need to adapt low-temperature performance additives to these new types of fuel bases and fuels, which are considered particularly difficult to process.

The present invention applies to fuels containing not only conventional distillates such as those resulting from the direct distillation of crude oils, but also to bases from other sources, such as those described above.

Thus, the purpose of the present invention is to propose novel additives and concentrates containing them which can advantageously be used as additives to improve the low-temperature performance of these fuels during their storage and/or their use at low temperatures, typically below 0° C.

The purpose of the present invention is to provide novel additives for fuels, and concentrates containing such additives, acting on the cold filter plugging point (CFPP).

Finally, another subject matter of the invention is to provide a fuel composition having improved low-temperature performance, in particular at temperatures below 0° C., preferably below −5° C.

SUBJECT MATTER OF THE INVENTION

The applicant has now discovered that particular crosslinked homopolymers or copolymers, as described below, have unexpected properties for lowering the cold filter plugging point of fuel compositions, including those that are particularly difficult to process.

The subject matter of the present invention is thus the use, for lowering the cold filter plugging point of a fuel composition, of one or more crosslinked polymers comprising at least one unit of the following formula (I):

wherein

R₁ represents a hydrogen atom or a methyl group,

E represents —O—CO—, or —CO—O— or —NH—CO— or —CO—NH—, and

G is a C₁ to C₃₄ alkyl group,

-   -   said copolymer having a degree of crosslinking, corresponding to         the amount in moles of crosslinking agent relative to the total         amount in moles of monomers in the polymer, excluding the         crosslinking agent, in the range from 0.5% to 30%.

According to a preferred embodiment, the above-defined polymer is used as a so-called “CFPP booster” additive, i.e. in combination with a cold flow improver (CFI), whose performance it improves.

Another subject matter of the invention is an additive composition comprising such a polymer in combination with a cold flow improver as described below, as well as an additive concentrate comprising such a composition. The cold flow improver is selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s), alone or as a mixture.

Another subject matter of the invention is a fuel composition comprising:

-   -   (1) at least one hydrocarbon cut from one or more sources         selected from the group consisting of mineral (preferably         petroleum), animal, plant and synthetic sources,     -   (2) at least one crosslinked polymer as defined above, and     -   (3) at least one cold flow improver selected from copolymers and         terpolymers of ethylene and vinyl and/or acrylic ester(s).

Other subject matters, features, aspects and advantages of the invention will become even clearer upon reading the following description and examples.

Hereinbelow, and unless otherwise indicated, the bounds of a range of values are included in that range, particularly in the expressions “between” and “from . . . to . . . ”.

In addition, the terms “at least one” and “at least” used in the present description are respectively equivalent to the terms “one or more” and “greater than or equal to”.

Finally, in a manner known per se, a CN compound is a compound containing N carbon atoms in its chemical structure.

DETAILED DESCRIPTION

The Crosslinked Polymer:

The invention uses a crosslinked polymer comprising at least one unit of the following formula (I):

wherein

R₁ represents a hydrogen atom or a methyl group,

E represents —O—CO—, or —CO—O— or —NH—CO— or —CO—NH—,

G is a C₁ to C₃₄ alkyl group.

The group E of the formula (I) is selected from:

-   -   E=—O—CO—, on the understanding that E is then linked to the         vinyl carbon by the oxygen atom;     -   E=—CO—O—, on the understanding that E is then linked to the         vinyl carbon by the carbon atom;     -   E=—NH—CO—, on the understanding that E is then linked to the         vinyl carbon through the nitrogen atom; and     -   E=—CO—NH—, on the understanding that E is then linked to the         vinyl carbon via the carbon atom.

According to a first embodiment, the group E of the formula (I) is selected from: —O—CO— and —NH—CO—, on the understanding that the group E=—O—CO— is linked to the vinyl carbon via the oxygen atom and that the group E=—NH—CO— is linked to the vinyl carbon via the nitrogen atom. In this embodiment, the group E of the formula (I) is preferably the group —O—CO—.

According to a second embodiment, the group E of the formula (I) is selected from: —CO—O— and —CO—NH—, on the understanding that the group E is linked to the vinyl carbon via the carbon atom. In this embodiment, the group E of the formula (I) is preferably the group —CO—O—

According to a particularly preferred embodiment, the group E is a group —CO—O—, E being linked to the vinyl carbon by the carbon atom.

The group G of the formula (I) is a C₁ to C₃₄ alkyl group, preferably a C₄ to C₃₄, more preferably C₄ to C₃₀, more preferentially C₆ to C₂₄, even more preferentially C₈ to C₂₂ alkyl radical. The alkyl radical is a linear or branched, cyclic or acyclic, preferably acyclic radical. This alkyl radical may comprise a linear or branched part and a cyclic part.

The group G of the formula (I) is advantageously a linear or branched acyclic C₁ to C₃₄, preferably C₄ to C₃₄, more preferentially C₄ to C₃₀, more preferentially C₆ to C₂₄, even more preferentially C₈ to C₂₂, and even better C₁₂ to C₁₄ or C₁₈ to C₂₂ alkyl radical. The embodiment in which the group G is a linear or branched acyclic C₁₂ to C₁₄ alkyl radical is particularly preferred.

Non-limiting mention may be made of alkyl groups such as butyl, octyl, decyl, dodecyl, ethyl-2-hexyl, isooctyl, isodecyl and isododecyl, C₁₄ alkyl groups, C₁₆ alkyl groups and C₁₈ alkyl groups.

According to a particularly preferred embodiment, the group E is a group —CO—O—, E being linked to the vinyl carbon via the carbon atom, and the group G is a linear or branched acyclic C₁ to C₃₄, preferably C₄ to C₃₀, more preferentially C₆ to C₂₄, even more preferentially C₈ to C₂₂, and even better C₁₂ to C₁₄ or C₁₈ to C₂₂ alkyl radical. The embodiment in which the group G is a linear or branched acyclic C₁₂ to C₁₄ alkyl radical is particularly preferred.

The units according to this embodiment correspond to those derived from monomers selected from among the C₁ to C₃₄, preferably C₄ to C₃₀, more preferentially C₆ to C₂₄, even more preferentially C₈ to C₂₂, and even better C₁₂ to C₁₄ or C₁₈ to C₂₂ alkyl acrylates and methacrylates.

The crosslinked polymer can be a homopolymer or a copolymer.

In this case of a copolymer, the polymer according to the invention may comprise several (at least two) different units of the formula (I) as described above and/or additional units, different from the units of the formula (I) above.

Such additional units are preferably derived from polar monomers, such as in particular one or more vinyl monomers carrying a polar substituent.

Preferred polar monomers include:

-   -   2-phenoxyethylacrylate:

-   -   1-vinylimidazole:

-   -   N-vinylpyrrolidone:

The copolymer according to the invention advantageously contains at least 50 mol % of units of the formula (I), preferably at least 70 mol %. The copolymer preferably contains 50 to 80 mol % of units of the formula (I).

When the polymer according to the invention is a copolymer, it may be selected from block copolymers and statistical copolymers, preferably statistical copolymers.

The polymer according to the invention has the characteristic feature of being crosslinked. The degree of crosslinking, corresponding to the amount in moles of crosslinking agent relative to the total amount in moles of monomers in the polymer, excluding the crosslinking agent, is from 0.5% to 30%, preferably from 1% to 20%, more preferentially from 2% to 10%, and even better from 3% to 6%.

The crosslinking agent may be any compound capable of allowing the crosslinking of polymers comprising units of the formula (I) as described above. Numerous crosslinking agents exist and are well known to the person skilled in the art.

According to a preferred embodiment, the crosslinking agent is selected from divinyl compounds, and more preferentially from diacrylates and dimethacrylates of the following formula (III):

with R representing a hydrocarbon chain comprising from 2 to 16 and preferably from 3 to 12 carbon atoms, which may be interrupted by one or more heteroatoms selected from N and O, and which may be substituted by one or more —OZ groups with Z representing a hydrogen atom or a C₁ to C₄ alkyl radical, and R₂ and R₃ independently representing a hydrogen atom or a methyl group.

Non-limiting examples of particularly preferred crosslinking agents include:

1,6-hexanediol dimethacrylate, of the formula:

-   -   di(ethylene glycol) dimethacrylate, of the formula:

-   -   glycerol dimethacrylate, of the formula:

-   -   1,6-hexanediol diacrylate, of the formula:

-   -   di(ethylene glycol) diacrylate, of the formula:

-   -   the 1,6-hexanediol ethoxylate diacrylate of the formula:

The polymer used in the present invention can be obtained by homopolymerization or copolymerization of at least one monomer corresponding to the following formula (II):

wherein

-   -   R₁, E and G are as defined above, the preferred variants of R₁,         E and G according to the formula (I) described above being also         preferred variants of the formula (II).

When the group E of the monomer of the formula (II) is the group —O—CO—, on the understanding that the group —O—CO— is linked to the vinyl carbon via the oxygen atom, the monomer of the formula (II) is preferably selected from C1 to C34, preferably C4 to C30, more preferentially C6 to C24, more preferentially C8 to C22, even better C12 to C14 or C18 to C22 and even more preferentially C12 to C14 alkyl vinyl esters. The alkyl radical of the vinyl alkyl ester is linear or branched, cyclic or acyclic, preferably acyclic.

Examples of vinyl alkyl ester monomers include vinyl octanoate, vinyl decanoate, vinyl dodecanoate, vinyl tetradecanoate, vinyl hexadecanoate, vinyl octodecanoate, vinyl docosanoate, vinyl 2-ethylhexanoate.

When the group E of the monomer of the formula (II) is the group —CO—O—, on the understanding that the group —CO—O— is linked to the vinyl carbon via the carbon atom, the monomer of the formula (II) is preferably selected from C1 to C34, preferably C4 to C30, more preferentially C6 to C24, more preferentially C8 to C22 and even better C12 to C14 or C18 to C22 alkyl acrylates or methacrylates, and even more preferentially C12 to C14 alkyl acrylates or methacrylates. The alkyl radical of the acrylate or methacrylate is linear or branched, cyclic or acyclic, preferably acyclic.

Non-limiting examples of the alkyl (meth)acrylates which may be used as monomers in the manufacture of the polymer of the invention include: n-octyl acrylate, n-octyl methacrylate, n-decyl acrylate, n-decyl methacrylate, n-dodecyl acrylate, n-dodecyl methacrylate, ethyl-2-hexyl acrylate, ethyl-2-hexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, isodecyl acrylate, isodecyl methacrylate, C12 to C14 or C18 to C22 alkyl acrylates and C12 to C14 or C18 to C22 alkyl methacrylates. It is particularly preferred to use C12 to C14 alkyl acrylates and C12 to C14 alkyl methacrylates, C18 to C22 alkyl acrylates and C18 to C22 alkyl methacrylates.

It is understood that it would be within the scope of the invention if the polymer according to the invention were obtained from monomers different from those of the formula (II) above, insofar as the final polymer corresponds to a crosslinked polymer as defined above. For example, it would be within the scope of the invention if the polymer were obtained by polymerization of different monomers, followed by post-functionalization. For example, the units of the formula (I) can be obtained from acrylic acid by a transesterification reaction.

The polymer according to the invention can be prepared by any known polymerization process. The various polymerization and crosslinking techniques and conditions are widely described in the literature and fall within the general knowledge of the person skilled in the art.

The polymerization is, advantageously, a controlled radical polymerization; for example, atom transfer radical polymerization (ATRP); nitroxide-mediated polymerization (NMP); degenerative transfer processes such as iodine transfer radical polymerization (ITRP) or reversible addition-fragmentation chain transfer (RAFT); ATRP-derived polymerizations such as polymerizations using initiators for continuous activator regeneration (ICAR) or using activators regenerated by electron transfer (ARGET).

Reversible addition-fragmentation chain transfer (RAFT) is a living radical polymerization technique. The RAFT technique was discovered in 1988 by Australia's national science research agency CSIRO (J. Chiefari et al., Macromolecules, 1998, 31, 5559). The RAFT technique very quickly became the subject of intensive research by the scientific community as it allows the synthesis of macromolecules with complex architectures, including block, graft, comb and star structures, while making it possible to control the molecular mass of the macromolecules obtained (G. Moad et al., Aust. J. Chem, 2005, 58, 379). RAFT polymerization can be applied to a very wide range of vinyl monomers and under a variety of experimental conditions, including the preparation of water-soluble materials (C. L. McCormick et al., Acc. Chem. Res. 2004, 37, 312). The RAFT process involves the conventional free radical polymerization of a substituted monomer in the presence of a suitable chain transfer agent (CTA). Commonly used RAFT agents include thiocarbonylthio compounds such as dithioesters (J. Chiefari et al., Macromolecules, 1998, 31, 5559), dithiocarbamates (R. T. A. Mayadunne et al., Macromolecules, 1999, 32, 6977; M. Destarac et al., Macromol. Rapid. Commun. 2000, 21, 1035), trithiocarbonates (R. T. A. Mayadunne et al., Macromolecules, 2000, 33, 243) and xanthates (R. Francis et al., Macromolecules, 2000, 33, 4699), which polymerize by a reversible chain transfer process. The use of a suitable RAFT agent allows the synthesis of polymers with a high degree of functionality and a narrow molecular weight distribution, i.e. a low polydispersity index (PDI).

Examples of RAFT radical polymerization descriptions are the documents WO1998/01478, WO1999/31144, WO2001/77198, WO2005/00319, WO2005/000924.

The crosslinked polymer according to the invention has, advantageously, a weight-average molar mass (Mw) between 10 000 and 100 000 g/mol, preferably between 10 000 and 50 000 g/mol, and more preferentially between 11 000 and 35 000 g/mol.

The crosslinked polymer according to the invention has, advantageously, a number-average molar mass (Mn) between 2 000 and 16 000 g/mol.

The number- and weight-average molar masses are measured by size-exclusion chromatography (SEC).

Use:

The crosslinked polymer described above is used to lower the cold filter plugging point of a fuel composition, in particular of a composition selected from diesels, biodiesels, Bx type diesels and fuel oils such as preferably domestic heating oils (DHO).

The cold filter plugging point, or CFPP, is measured according to standard NF EN 116.

The fuel composition is as described below and advantageously comprises at least one hydrocarbon cut from one or more sources selected from the group consisting of mineral, preferably petroleum, animal, vegetable and synthetic sources.

According to a preferred embodiment, the crosslinked polymer according to the invention is used as a CFPP booster additive, i.e. in combination with at least one cold flow improver (CFI).

The cold flow improver (CFI) is selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s), alone or in a mixture.

In this embodiment, the crosslinked polymer according to the invention is used to amplify the fluidizing effect of the cold flow improver by lowering the cold filter plugging point (CFPP).

This effect is commonly referred to as the “CFPP booster effect” as the presence of the crosslinked polymer improves the fluidizing performance of the CFI additive. This improvement is reflected, in particular, by a significant decrease in the CFPP of the fuel composition additized with this combination compared with the same fuel composition additized only with the CFI additive, at the same treatment rate. Generally, a significant decrease in the CFPP is expressed as a decrease of at least 3° C. in the CFPP according to standard NF EN 116.

According to a particularly preferred embodiment, the crosslinked polymer is used to amplify the fluidizing (flow) effect of the cold flow improver (CFI) by improving the cold filter plugging point (CFPP) of the fuel, the CFPP being measured according to standard NF EN 116.

The crosslinked polymer may be added to fuels within the refinery, and/or may be incorporated downstream of the refinery, optionally in a mixture with other additives, in the form of an additive concentrate, also known as an “additive package” depending on usage.

The crosslinked polymer is advantageously used in the fuel in a content of at least 2 ppm by weight, preferably at least 3 ppm by weight, and better still at least 5 ppm by weight, more preferentially in a content of 2 to 100 ppm by weight, more preferentially 3 to 50 ppm by weight, and better still 3 to 10 ppm by weight, based on the total weight of the fuel composition. The units mentioned in ppm in the present application are ppm by weight unless otherwise specified.

The Additive Composition:

The invention also relates to an additive composition comprising a crosslinked polymer as described above, and one or more cold flow improver(s).

The cold flow improver (CFI) is selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s), alone or in a mixture. By way of example, mention may be made of ethylene/unsaturated ester copolymers, such as ethylene/vinyl acetate (EVA), ethylene/vinyl propionate (EVP), ethylene/vinyl ethanoate (EVE), ethylene/methyl methacrylate (EMMA), and ethylene/alkyl fumarate copolymers described, for example, in the documents U.S. Pat. Nos. 3,048,479, 3,627,838, 3,790,359, 3,961,961 and EP261957.

According to a preferred embodiment, the cold flow improver (CFI) is selected from copolymers of ethylene and vinyl ester(s), alone or in a mixture, in particular ethylene/vinyl acetate (EVA) and ethylene/vinyl propionate (EVP) copolymers, more preferably ethylene/vinyl acetate (EVA) copolymers.

The additive composition may also include one or more other additives commonly used in fuels, different from the crosslinked polymer and cold flow improvers described above.

The additive composition may, typically, include one or more other additives selected from detergents, anti-corrosion agents, dispersants, demulsifiers, antifoam agents, biocides, reodorants, cetane number improvers, friction modifiers, lubricity or smoothness additives, combustion aids (catalytic combustion and soot promoters), anti-sedimentation agents, anti-wear agents and/or conductivity modifiers.

Among these additives, particular mention may be made of:

a) cetane number improvers, in particular (but not limited to) selected from alkyl nitrates, preferably 2-ethyl hexyl nitrate, aryl peroxides, preferably benzyl peroxide, and alkyl peroxides, preferably tert-butyl peroxide;

b) anti-foaming additives, including (but not limited to) those selected from polysiloxanes, oxyalkylated polysiloxanes, and fatty acid amides derived from vegetable or animal oils. Examples of such additives are given in EP861882, EP663000, EP736590;

c) detergent and/or anti-corrosion additives, including (but not limited to) those selected from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkyl polyamines, polyetheramines, quaternary ammonium salts and triazole derivatives; examples of such additives are given in the following documents: EP0938535, US2012/0010112 and WO2012/004300.

d) lubricity additives or anti-wear agents, including (but not limited to) those selected from the group consisting of fatty acids and their ester or amide derivatives, including glycerol monooleate, and mono- and polycyclic carboxylic acid derivatives. Examples of such additives are given in the following documents: EP680506, EP860494, WO98/04656, EP915944, FR2772783, FR2772784.

e) anti-sedimentation additives and/or paraffin dispersants, in particular (but not limited to) selected from the group consisting of (meth)acrylic acid/alkyl (meth)acrylate copolymers amidified by a polyamine, polyamine alkenylsuccinimides, phthalamic acid and double-chain fatty amine derivatives; alkylphenol resins. Examples of such additives are given in the following documents: EP261959, EP593331, EP674689, EP327423, EP512889, EP832172; US2005/0223631; U.S. Pat. No. 5,998,530; WO93/14178.

The additive composition may advantageously comprise from 0.3 to 30 wt % of crosslinked polymer as described above, based on the total weight of the additive composition.

The present invention also relates to an additive concentrate comprising an additive composition as described above, in admixture with an organic liquid. The organic liquid is advantageously inert with respect to the constituents of the additive composition, and miscible with fuels, in particular those from one or more sources selected from the group consisting of mineral, preferably petroleum, animal, vegetable and synthetic sources.

The organic liquid is preferably selected from aromatic hydrocarbon solvents such as the solvent marketed under the name “SOLVESSO”, alcohols, ethers and other oxygenated compounds, and paraffinic solvents such as hexane, pentane or isoparaffins, alone or as a mixture.

The Fuel Composition:

The invention also relates to a fuel composition, comprising:

at least one hydrocarbon cut from one or more sources selected from the group consisting of mineral, animal, vegetable and synthetic sources,

at least one crosslinked polymer as defined above, and

at least one cold flow improver selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s).

The mineral sources are preferably oil.

The fuel composition according to the invention advantageously comprises the crosslinked polymer(s) in a content of at least 2 ppm by weight, preferably at least 3 ppm, and even better at least 5 ppm, more preferentially in a content ranging from 2 to 100 ppm, even more preferentially from 3 to 50 ppm, and even better from 3 to 10 ppm by weight.

According to a preferred embodiment, the cold flow improver(s) is (are) selected from ethylene/vinyl acetate (EVA), ethylene/vinyl propionate (EVP), ethylene/vinyl ethanoate (EVE), ethylene/methyl methacrylate (EMMA) copolymers; and more preferentially among ethylene/vinyl acetate (EVA) and ethylene/vinyl propionate (EVP) copolymers; still more preferentially among ethylene/vinyl acetate (EVA) copolymers.

The composition advantageously contains at least 20 ppm by weight, preferably at least 50 ppm, advantageously between 20 and 5000 ppm, more preferentially between 50 and 1000 ppm by weight of cold flow improver(s).

The fuels may be selected from liquid hydrocarbon fuels alone or in a mixture. Liquid hydrocarbon fuels include middle distillates with a boiling point between 100 and 500° C. Such distillates may, for example, be selected from distillates obtained by direct distillation of crude hydrocarbons, vacuum distillates, hydrotreated distillates, distillates from catalytic cracking and/or hydrocracking of vacuum distillates, distillates from atmospheric residue desulfurization (ARDS) and/or visbreaking conversion processes, distillates resulting from the recovery of Fischer-Tropsch cuts, distillates resulting from the biomass-to-liquid (BTL) conversion of plant and/or animal biomass, taken alone or in combination, and/or biodiesels of animal and/or plant origin and/or vegetable and/or animal oils and/or esters.

The sulfur content of the fuels is preferably less than 5000 ppm by weight, preferably less than 500 ppm, and more preferentially less than 50 ppm, or even less than 10 ppm and advantageously sulfur-free.

The fuel is preferably selected from diesels, biodiesels, Bx type diesels and fuel oils such as preferably domestic heating oils (DHO).

Bx type diesel fuel for a diesel engine (compression engine) means a diesel fuel which contains x % (v/v) of esters of vegetable or animal oils (including used cooking oil) transformed by a chemical process called transesterification which reacts this oil with an alcohol to obtain fatty acid esters (FAE). With methanol and ethanol, fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE) are obtained, respectively. The letter ‘B’ followed by a number x ranging from 0 to 100 indicates the percentage of FAE contained in the diesel fuel. For example, a B99 contains 99% FAE and 1% middle distillates of fossil origin, a B20 contains 20% FAE and 80% middle distillates of fossil origin, etc. . . . A distinction is therefore made between BO type diesel fuels which do not contain oxygenated compounds, and Bx type diesel fuels which contain x % (v/v) of vegetable oil or fatty acid esters, most often methyl esters (VOME or FAME). When FAE is used alone in engines, the fuel is referred to as B100.

The fuel may also contain hydrogenated vegetable oils, known to the industry as hydrogenated vegetable oil (HVO) or hydrogenation-derived renewable diesel (HDRD).

According to a particular embodiment, the fuel is selected from diesels, biodiesels and Bx type diesels, hydrogenated vegetable oils (HVO), and mixtures thereof.

The fuel composition may also contain one or more additional additives, different from the crosslinked polymers and cold flow improvers described above. Such additives may be selected from detergents, anti-corrosion agents, dispersants, demulsifiers, antifoam agents, biocides, reodorants, cetane number improvers, friction modifiers, lubricity or smoothness additives, combustion aids (catalytic combustion and soot promoters), anti-sedimentation agents, anti-wear agents and/or conductivity modifiers.

These additional additives may generally be present in amounts ranging from 50 to 1000 ppm by weight (each).

According to another embodiment of the invention, a process for lowering the cold filter plugging point of a fuel composition comprises a step of treating said composition with at least one crosslinked polymer as described above, and with one or more cold flow improver(s) selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s).

According to a preferred embodiment, such a process comprises the successive steps of:

a) determining an additive composition(s) most suitable for the fuel composition to be treated as well as the treatment rate required to achieve a maximum cold filter plugging point value for the specific fuel composition, said additive composition(s) comprising at least one crosslinked polymer according to the invention and at least one cold flow improver (CFI);

b) treating the fuel composition with the amount determined in step a) of said additive composition(s).

The process according to the invention is typically intended for a fuel composition as described above.

Step a) is carried out by any known process and is standard practice in the field of fuel additivation. This step involves defining a target value and then determining the improvement that is required to meet the specification.

In particular, the specification is a maximum CFPP according to the standard NF EN 116. The determination of the amount of additive(s) composition to be added to the fuel composition to achieve the specification will typically be carried out by comparison with the fuel composition without said additive(s) composition.

The amount of crosslinked polymer required to treat the fuel composition may vary according to the nature and origin of the fuel, in particular according to the level and nature of the paraffinic compounds it contains. The nature and origin of the fuel may therefore also be a factor to be considered in step a).

The above process may also include an additional step after step b) to verify the target achieved and/or adjust the rate of treatment with the additive(s) composition.

The following examples are given by way of illustration of the invention and should not be interpreted in such a way as to limit its scope.

EXAMPLES Example 1: Synthesis of Crosslinked and Non-Crosslinked Polymers Containing Units of the Formula (I)

Non-Crosslinked C12/C14 Alkyl Methacrylate Homopolymer (Comparative):

7.0 g (0.0262 mol) of C12/C14 alkyl methacrylate monomer is introduced into a 50 mL single-neck round-bottom flask, then 0.299 g (0.00135 mol) of RAFT agent (2-cyano-2-propyl benzodithioate) and 4.12 g (4.0 mL) of 1,4-dioxane are added. The monomer concentration is set at 2.0 mol/L. The flask is then degassed for 30 min under nitrogen and magnetic stirring and sealed. At the same time, 0.0286 g (1.74·10-4 mol) of azobis isobutyronitrile (AIBN) is introduced into a second 25 mL flask, together with 1.03 g (1.0 mL) of 1,4-dioxane as dissolution solvent. The second flask is in turn degassed for 30 minutes under nitrogen. The AIBN solution is then transferred with a nitrogen-purged syringe to the 50 mL flask, previously heated to 80° C., to start polymerization. The reaction is left for 24 h. Once polymerization is complete, the solvent is evaporated under reduced pressure (55 mbar) at 60° C. to recover the polymer.

Crosslinked C12/C14 Alkyl Methacrylate Homopolymer (in Accordance with the Invention):

7.0 g (0.0262 mol) of C12/C14 alkyl methacrylate monomer is introduced into a 50 mL single-neck round-bottom flask, then 0.285 g (0.00129 mol) of RAFT agent (2-cyano-2-propyl benzodithioate), 0.340 g (0.00131 mol) of 1,6-hexanediol dimethacrylate crosslinking agent and 16.3 g (15.8 mL) of 1,4-dioxane are added. The monomer concentration is set at 1.0 mol/L. The flask is then degassed for 30 minutes under nitrogen and magnetic stirring and sealed. At the same time, 0.0270 g (1.61·10-4 mol) of AIBN is added to a second 25 mL flask, together with 2.0 g (1.94 mL) of 1,4-dioxane as the dissolution solvent. The second flask is in turn degassed for 30 minutes under nitrogen. The AIBN solution is then transferred with a nitrogen-purged syringe to the 50 mL flask, previously heated to 80° C., to start polymerization. The reaction is left for 24 h. Once polymerization is complete, the solvent is evaporated under reduced pressure (55 mbar) at 60° C. to recover the crosslinked polymer.

Crosslinked C12/C14 Alkyl Acrylate—1-Vinylimidazole Copolymer (in Accordance with the Invention):

10.9 g (0.044 mol) of C12/C14 alkyl acrylate monomer and 1.03 g (0.0109 mol) of a second N-vinylimidazole monomer are introduced into a 50 mL single-neck round-bottom flask, then 0.548 g (0.00263 mol) of RAFT agent (2-cyano-2-propyl dodecyl trithiocarbonate), 0.589 g (0.00275 mol) of crosslinking agent and 19.8 g (19.2 mL) of 1,4-dioxane are added. The total concentration of the two monomers is set at 1.5 mol/L. The flask is then degassed for 30 minutes under nitrogen and magnetic stirring and sealed. At the same time, 0.051 g (3.1.10-4 mol) of AIBN is introduced into a second 25 mL flask, together with 2.0 g (1.94 mL) of 1,4-dioxane as the dissolution solvent. The second flask is in turn degassed for 30 minutes under nitrogen. The AIBN solution is then transferred with a nitrogen-purged syringe to the 50 mL flask, previously heated to 80° C., to start polymerization. The reaction is left for 24 h. Once polymerization is complete, the solvent is evaporated under reduced pressure (55 mbar) at 60° C. to recover the crosslinked copolymer.

A non-crosslinked C12/C14 alkyl acrylate homopolymer (comparative), as well as additional crosslinked C12/C14 alkyl acrylate homopolymers (in accordance with the invention) and additional crosslinked C12/C14 alkyl acrylate-1-vinylimidazole copolymers (in accordance with the invention) were synthesized, following synthesis protocols similar to those described above.

The characteristics of all the polymers synthesized are gathered in the table below:

Crosslinking agent + degree of M_(w) M_(n) Ð (dis- Polymer crosslinking (g/mol) (g/mol) persity) C₁₂/C₁₄ alkyl NO crosslinking 9600 8000 1.2 methacrylate agent homopolymer C₁₂/C₁₄ alkyl 1,6-hexanediol 34100 15300 2.23 methacrylate dimethacrylate, homopolymer 5% C₁₂/C₁₄ alkyl acrylate NO crosslinking 8000 7000 1.14 homopolymer agent C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol 16800 10600 1.58 homopolymer diacrylate, 5% C₁₂/C₁₄ alkyl acrylate di(ethyleneglycol) 13000 9400 1.38 homopolymer diacrylate, 5% C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol 28300 12600 2.24 homopolymer ethoxylate diacrylate, 5% C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol 11900 7500 1.59 copolymer (80 mol %)- diacrylate, 5% 1-vinylimidazole (20 mol %) C₁₂/C₁₄ alkyl acrylate di(ethyleneglycol) 11000 7200 1.53 copolymer (85 mol %)- diacrylate, 5% 1-vinylimidazole (15 mol %) C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol 11800 7100 1.66 copolymer (80 mol %)- ethoxylate 1-vinylimidazole diacrylate, 5% (20 mol %)

Example 2: Evaluation of Low-Temperature Performance

The polymers described in Example 1 were tested as low-temperature performance additives in a composition G of diesel type fuel which is particularly difficult to process and whose characteristics are detailed in the table below:

Characteristic Method Value Density at 15° C.  ISO 12185 831.2 kg/m³ Viscosity at 20° C. ISO 3104  5.1 mm²/s Viscosity at 40° C. ISO 3104  3.5 mm²/s Cloud point (CP)°  EN 23015 −3° C. Cold filter plugging point EN 116  −2° C. (CFPP) Pour point (PP) ASTM D 7346 −12° C.  Paraffin content 21.42 wt % Content of C16+ n-paraffins. 11.30 wt % Distillation profile D86 ISO 3405 Initial point 173.0° C. Point at 5% vol.  196.6° C. Point at 10% vol. 215.4° C. Point at 20% vol. 243.4° C. Point at 30% vol. 261.9° C. Point at 40% vol. 276.0° C. Point at 50% vol. 287.7° C. Point at 60% vol. 299.3° C. Point at 70% vol. 311.4° C. Point at 80% vol. 325.5° C. Point at 90% vol. 343.7° C. Point at 95% vol. 356.2° C. Final point 359.0° C. Distilled volume 97.4 mL Residue  0.6 mL Losses  1.8 mL

The diesel fuel composition G was additized with a package containing the following two conventional commercial cold flow improver (CFI) additives, in Solvesso 150 solvent:

0.5 wt % of the additive CP7956C marketed by Total Additifs Carburants Spéciaux, which is an ethylene/vinyl acetate (EVA) copolymer;

0.5 wt % of the additive Dodiflow D4134 marketed by the company Clariant, which is an ethylene/vinyl acetate/vinyl neodecanoate terpolymer.

This package was incorporated into the diesel fuel composition G at a content of 300 ppm by weight of active ingredient (i.e. 150 ppm by weight of each additive) based on the total weight of the diesel fuel composition.

The additized diesel fuel composition G1 was thus obtained.

The performance of each of the polymers in Example 1 as cold-temperature performance additives was tested by evaluating their ability to lower the cold filter plugging point (CFPP) of the additized diesel fuel composition G1.

Each polymer was added at a level of 3 ppm by weight to the composition G1, to give the diesel fuel G2, whose CFPP was then measured in accordance with standard EN 116.

The results obtained are shown in the table below:

CFPP Difference (° C.) in CFPP: Crosslinking diesel CFPP G1- Polymer agent G2 CFPP G2 C₁₂/C₁₄ alkyl NO crosslinking −12 1 methacrylate agent homopolymer C₁₂/C₁₄ alkyl 1,6-hexanediol methacrylate dimethacrylate −16 5 homopolymer C₁₂/C₁₄ alkyl acrylate NO crosslinking −11 0 homopolymer agent C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol homopolymer diacrylate −14 3 C₁₂/C₁₄ alkyl acrylate di(ethyleneglycol) homopolymer diacrylate −14 3 C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol homopolymer ethoxylate −15 4 diacrylate C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol copolymer- diacrylate −16 5 1-vinylimidazole C₁₂/C₁₄ alkyl acrylate di(ethyleneglycol) copolymer- diacrylate −16 5 1-vinylimidazole C₁₂/C₁₄ alkyl acrylate 1,6-hexanediol copolymer- ethoxylate −15 4 1-vinylimidazole diacrylate

The above results show that the use of the crosslinked polymers according to the invention leads to a significant lowering of the CFPP, ranging from 3 to 5 points. Surprisingly, crosslinked polymers give better results than non-crosslinked polymers. 

1. The use, for lowering the cold filter plugging point, measured according to standard NF EN 116, of a fuel composition, of one or more crosslinked polymers comprising at least one unit of the following formula (I):

wherein R₁ represents a hydrogen atom or a methyl group, E represents —O—CO—, or —CO—O— or —NH—CO— or —CO—NH—, G represents a C₁ to C₃₄ alkyl group, said copolymer having a degree of crosslinking, corresponding to the amount in moles of crosslinking agent relative to the total amount in moles of monomers in the polymer, excluding the crosslinking agent, in the range from 0.5% to 30%.
 2. (canceled)
 3. The use as claimed in claim 1, characterized in that the group E of the formula (I) is selected from: —CO—O— and —CO—NH—, on the understanding that the group E is linked to the vinyl carbon via the carbon atom, and preferably the group E of the formula (I) is the group —CO—O—.
 4. The use as recited in claim 1, characterized in that the group G of the formula (I) is a linear or branched acyclic C₁ to C₃₄, preferably C₄ to C₃₄, more preferentially C₄ to C₃₀, more preferentially C₆ to C₂₄, even more preferentially C₈ to C₂₂, even better C₁₂ to C₁₄ or C₁₈ to C₂₂, and even more preferentially C₁₂ to C₁₄ alkyl radical.
 5. The use as recited in claim 4, characterized in that the group E is a group —CO—O—, E being connected to the vinyl carbon via the carbon atom, and the group G is a linear or branched acyclic C₁ to C₃₄, preferably C₄ to C₃₀, more preferentially C₆ to C₂₄, even more preferentially C₈ to C₂₂, and even better C₁₂ to C₁₄ or C₁₈ to C₂₂, and even more preferentially C₁₂ to C₁₄ alkyl radical.
 6. The use as recited in claim 1, characterized in that the crosslinked polymer is a homopolymer.
 7. The use as recited in claim 1, characterized in that the crosslinked polymer is a copolymer selected from block copolymers and statistical copolymers, preferably from statistical copolymers.
 8. (canceled)
 9. The use as recited in claim 7, characterized in that the polymer comprises additional units different from the units of the formula (I), preferably units derived from one or more vinyl monomers carrying a polar substituent.
 10. The use as recited in claim 9, characterized in that the polymer comprises units derived from one or more vinyl monomers selected from: 2-phenoxyethylacrylate:

1-vinylimidazole:

N-vinylpyrrolidone:


11. The use as recited in claim 7, characterized in that the copolymer contains at least 50 mol % of units of the formula (I), preferably at least 70 mol %.
 12. The use as recited in claim 1, characterized in that the polymer has a degree of crosslinking in the range from 1% to 20%, more preferentially from 2% to 10%, and even better from 3% to 6%.
 13. The use as recited in claim 1, characterized in that the crosslinking agent of the polymer is selected from divinyl compounds, and preferably from diacrylates and dimethacrylates of the following formula (III):

with R representing a hydrocarbon chain comprising from 2 to 16 and preferably from 3 to 12 carbon atoms, which may be interrupted by one or more heteroatoms selected from N and O, and which may be substituted by one or more —OZ groups with Z representing a hydrogen atom or a C₁ to C₄ alkyl radical, and R₂ and R₃ independently representing a hydrogen atom or a methyl group.
 14. The use as recited in claim 13, characterized in that the crosslinking agent is selected from 1,6-hexanediol dimethacrylate; di(ethylene glycol) dimethacrylate; glycerol dimethacrylate; 1,6-hexanediol diacrylate; di(ethylene glycol) diacrylate; and 1,6-hexanediol ethoxylate diacrylate.
 15. The use as recited in claim 1, characterized in that the fuel composition is selected from diesels, biodiesel, B_(x) type diesels and fuel oils such as domestic heating oils (DHO).
 16. The use as recited in claim 1, characterized in that said crosslinked polymer is used in combination with at least one cold flow improver selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s), alone or as a mixture, preferably from ethylene/vinyl acetate (EVA), ethylene/vinyl propionate (EVP), ethylene/vinyl ethanoate (EVE) and ethylene/methyl methacrylate (EMMA) copolymers; and more preferentially among ethylene/vinyl acetate (EVA) and ethylene/vinyl propionate (EVP) copolymers; still more preferentially among ethylene/vinyl acetate (EVA) copolymers.
 17. The use as recited in claim 1, characterized in that said crosslinked polymer is used in a content ranging from 2 to 100 ppm by weight, even more preferentially from 3 to 50 ppm by weight, and even better from 3 to 10 ppm by weight, based on the total weight of the fuel composition.
 18. An additive composition comprising a crosslinked polymer as defined in claim 1, and one or more cold flow improver(s) selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s); preferably among ethylene/vinyl acetate (EVA), ethylene/vinyl propionate (EVP), ethylene/vinyl ethanoate (EVE), ethylene/methyl methacrylate (EMMA) copolymers; and more preferentially among ethylene/vinyl acetate (EVA) and ethylene/vinyl propionate (EVP) copolymers; and more preferentially still among ethylene/vinyl acetate (EVA) copolymers.
 19. (canceled)
 20. (canceled)
 21. A fuel composition comprising: (1) at least one hydrocarbon cut from one or more sources selected from the group consisting of mineral, animal, vegetable and synthetic sources, (2) at least one crosslinked polymer as defined in claim 1, and (3) at least one cold flow improver selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s).
 22. (canceled)
 23. The composition recited in claim 21, characterized in that it contains the crosslinked polymer(s) in a content of 2 to 100 ppm by weight, even more preferentially 3 to 50 ppm by weight, and even better 3 to 10 ppm by weight.
 24. The composition as recited in claim 21, characterized in that the cold flow improver(s) is (are) selected from ethylene/vinyl acetate (EVA), ethylene/vinyl propionate (EVP), ethylene/vinyl ethanoate (EVE), ethylene/methyl methacrylate (EMMA) copolymers; and more preferentially among ethylene/vinyl acetate (EVA) and ethylene/vinyl propionate (EVP) copolymers; even more preferentially among ethylene/vinyl acetate (EVA) copolymers.
 25. (canceled)
 26. A process for lowering the cold filter plugging point of a fuel composition comprising a step of treating said composition with at least one crosslinked polymer as defined in claim 1, and with one or more cold flow improver(s) selected from copolymers and terpolymers of ethylene and vinyl and/or acrylic ester(s). 